Recording and reproducing of sound



July 9, 1940. A. N. GoLDsMlTH RECORDING AND REPRODUCING OF SOUND 4 sheets-sheet 2 I Filed July 27, 1935 f INVENTOR Azffo A1. @0L @5M/7H yBY gg ATTORNEY July 9,'1940. A. N. GoLDsMrrH RECORDING AND REPRODUCING 0F SOUND Filed July 27, 1935 4 Sheets-Sheet l5 DDDEDDD DDDDDDED H Dmmm ZDDDDGEDD UDDDDEDEDDDDDDDDEEDDDD ATTORNEY July 9, 1940- A. N. GoLDsMlTH 2,207,249

RECORDING AND REPRODUCING OF SOUND rig. 0^

Patented July 9,' 1940 2,207,249 Y .l u RECORDING ANDI REPRODUCING or so-UND Alfred N. Goldsmith, NewYork', N. Y., 'assignor to Radio Corporation of America.,` a 'corpora=jtion of -Delaware application July 2v, 1935, serial No.' 33,491 I 5 Claims. (Cl. y1'79100.3)

rI 'his invention relates toY the recording and reproducing of sound or the like, and has for its rincipal object the provision of an improved Lsystem and methodof operation whereby sound reproduced in synchronismwith a moving picture is made to emanate automatically at or near the particuiar picture part or `character by whichv it appears to be produced. f

In one embodiment of the invention, sound is The recording elements utilized to produce the sound and control reco-rds may be of any suitable type. It is apparent that the auxiliary recording elements producing the volume 'control records,` however, do not require the same'high degree of accuracy as that producing the sound record for the reason that thev recorded control impulses `are less complicated. The'type of control record 1 produced 'may assume various forms such as a plurality of variable area or variable density tracks parallel with and adjacent to the sound track or a plurality of such tracks located between the picture frames. v

The invention will be better `understood from the following description when considered in connection with the accompanying drawings and its .scope will be pointed out in the appended claims.

Referring to the drawings:

Fig. 1 is a diagrammatic illustration of a sound recording system constructed in accordance with the invention,

Fig. 2 illustrates a type of composite record which may be produced by the system of Fig. l,

Fig. 3 illustrates a modified type of record, Fig. 4 illustrates diagrammatically one type of recording element suitable for producing the record tracks of Fig. 2,

Fig. 5 is a similar illustration of a recording element suitable for producing the record tracks of Fig. 3, and

Fig. 6 is a diagrammatic illustration of a system for reproducing the record of Fig. 2.

The recording system of Fig. 1 includes a plu-v rality of microphones I each connected to a mixer I3 through a separate audio current chan- -ponentwhich is supplied through a rectifier i6,

phones ,lil are located at :different points so as "topick up sounds. originating at diierent parts,

vord track in the usual manner, and the volume ling elements .or onthe'mannerof printing these yand maybe controlled as desired. .Y f

fthe formiof; a motion picturev Iilm,` the picture 25, 2S and 21. While these-variousrecords are y image is vibratedvby the mirror 33 to vcover more antro nelincluding a voluimecontrol device Il and an amplifier l2. The combined currents of the dif` ferent' channels arev suppliedy from Ythe mixer i3 throughanamplifier lli to a soundrecorder l which may be of any suitabletype. From each of f5 the ampliiiers l2 is derived' an audio current corna low pass nl ter il, a modulator'l and an oscillation generator i9 to an auxiliary recorder 2U,

2l or 22. f -10 In operating this recording system, the micro# of a-motion picturev scene or. the like, the. combined audio current outputs of the diierent mi- 15 crophone channels are recorded on a single rec.-

oi the current in each, channel Vis recorded on .a separate track of the record as a volume modulatedconstant frequency current.v Obviously the relative locations ofthe sound and control records longitudinally of therecord stripis dependent on the relation between the different recordrecords from the negative to the positive strip As. illustrated by Fig. 2, the record may be in frames being shown at 23, the compositeLsound record at 2li' and-the :volume'control records at 30 of the variable area type, they obviously may be of the variable density type, or of any other suitable type.

Fig. 3 illustrates a somewhatrdifferen'ttype of 35 record wherein the sound record 24 vis located on the usual marginal track and volume or sound location records are recorded between the picture frames. I

A recorder suitable for producing the record tracks of Fig. 2 is illustrated in Fig. 4. This recorder includes a lamp 3l from which light-passes'` throughy anoptical barrel 32 to the vibratable mirror 33 oi a recording galvanorneter. Light reected from the mirror 33V passes through a 45 lens 34, the light slit 35 of a screen 36 and lenses 31 to the surface of a record 38. As will be readily understood, the'barrel 32 inoludes'a mask provided With an aperture through which a light image 39 is projected on the screen 36 and this 50 or less of the slit depending on the current suppliedto the galvanometer. Fig. 5` illustrates one type of recorder suitable i for producing the record of Fig. 3. This recorder includes a mask 39A provided with a plurality of apertures 40 to 43. Arranged to cooperate with the apertures 40, 4l and 42 are a corresponding number of shutters 44, 45 and 46 which are operated respectively by solenoids 41, 48 and 49 each energized by volume control current supplied through a diierent one of the control channels. The different tracks produced by this recording element are indicated at 50, 5| and 5 2 and correspond respectively to the volumel of the sound at the microphones l0 of Fig. 1.

While the auxiliary or control 'recorder elements 2li, 2| and 22 may be located at different` points with respect to the main recorder element l5, they are preferably located between it and the take-up reel. If the various recording elements are arranged one afterA another longitudi` nally of the lm, it is of course` desirable that the records be reproduced by reproducer elements related in a corresponding manner.

Fig. 6 diagrammatically illustrates a .system suitable for reproducing the Arecor'ds previously described. This system includes a main reproducer 53-for reproducing the sound track and auxiliary or volume control reproducers 54, 55 and 56 for'reproducingthe .control records..` From theV main` reproducer 53 current is supplied through an amplier51 to an amplier and a loudspeaker 59,7 to a amplifier .60 and a loudspeaker EI and to an amplifier 62 anda loudspeaker 63. y i Y Volume control current derived from the auxiliary reproducer's .54, 55 and 56 is supplied through separate control channels each including an amplifier 64, a rectifier. 65 and a low-pass lter 66 tothe volumecontrol. devices `of the ampliers 58, 60-'and B2. Suitable types of volume controldevices are well known and their application to the improved reproducingsystem will be readily understood without detailed information. They function tomaintain between the sounds emitted by the loudspeakers 59, 6I and 63 the same volume relation as .that between the sounds originating at the microphones I0.

I claim: ,Y v

1. A sound recording system including a plurality of microphones spaced from one another .for picking up sound Aoriginating at different points, a sound recorder including' main and auxiliary recording elements,-means for energizing said main recording element vin accordance with the combined audio current outputs of said microphones, and means for energizing each of said auxiliary recorders in response to a Iconstant frequency current modulated in accordance with the volume of the audio current supplied by a corresponding one of said microphones.

2. A sound recording system including a plu- .ralityof microphones spaced from one another for picking up sound originating at different points, a sound recorder including main and K auxiliary recording elements, means for energizing said main recording element in accordance with the combined audio current'outputs of said microphones, and means including a lseriesconnected rectier and low frequency pass ilter for energizing each of said auxiliary recorders in response to va constant frequency current -modulated in accordance with the volume of the audio current supplied by a corresponding one of said microphones.

3. `A soundrecording system including a plurality of microphones spaced from one another .ifor pickingA up sound originating at different points, a sound recorder. including main and auxiliary. recording elements, means for energizing said main recording element in accordance with the combined audio current outputs of said rents, combining said currents, recording said combined currents on a single record track, and recording on separate record tracks constant frequency vcurrents each modulated in accordance with the volume of the current delivered by a .corresponding one of said microphones.

5. The sound recording method which includes converting sound originating at a plurality of different points into corr'esponding audio currents, combining said currents, recording said combined currents on a single record track, and

recording on lseparate record'tracks currents each modulated in accordance with the volumeofl the current delivered by a different one of said microphones.

ALFRED N. GOLDSMITI-L 

